Who is Pylades (from Electra) from Euripides V and what is their importance?

Pylades, a native of Phocis, becomes Orestes' friend in exile. He later accompanies Orestes back to Argos to avenge his father's death. Pylades is a presence in the play and has no speaking lines. In the end, the Dioscuri decree that Electra must marry Pylades and be exiled from Argos for killing her mother.